2303 Dynamic Response of Small Magnet encompassed with Magnetic Fluid in Magnetic Field

2006 ◽  
Vol 2006.2 (0) ◽  
pp. 19-20
Author(s):  
Seiichi SUDO ◽  
Yuichi KUROSU ◽  
Tetsuya YANO ◽  
Hirokatsu HONMA
Author(s):  
Azhar Iqbal ◽  
Foued Ben Amara

Magnetic fluid deformable mirrors (MFDMs) present a simple alternative to the expensive and delicate wavefront correctors currently in use in adaptive optics (AO) systems. Such mirrors are particularly suitable for retinal imaging AO systems. The practical implementation of a retinal imaging AO system incorporating a MFDM requires an effective control system to control the shape of the mirror surface. The real-time control of the mirror surface requires a model of the mirror that can be used to determine the dynamic response of the mirror to a magnetic field applied as the control input. This paper presents such a model that not only determines the dynamic response of the MFDM but also takes into account the unique requirements of the retinal imaging application of the mirrors. The mirror is modeled as a horizontal layer of a magnetic fluid. The dynamic response of the mirror to the applied magnetic field is represented by the deflection of the free surface of the layer. The surface deflection is determined by the modal analysis of the coupled fluid-magnetic system. Considering the requirements of the retinal imaging application, the effects of surface tension and depth of the fluid layer are duly represented in the model. The mirror model is described in a state-space form and can be readily used in the design of a controller to regulate the mirror surface shape.


2008 ◽  
Vol 44 (2) ◽  
pp. 175-182 ◽  
Author(s):  
K. Zimmermann ◽  
V.A. Naletova ◽  
I. Zeidis ◽  
V.A. Turkov ◽  
D.A. Pelevina ◽  
...  

2011 ◽  
Author(s):  
Peng Zu ◽  
Chi Chiu Chan ◽  
Yongxing Jin ◽  
Yifan Zhang ◽  
Xinyong Dong

2021 ◽  
Vol 143 ◽  
pp. 107264
Author(s):  
Junying Zhang ◽  
Fengyi Chen ◽  
Ruohui Wang ◽  
Xueguang Qiao ◽  
Haibin Chen ◽  
...  

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1870
Author(s):  
Dmitry Borin ◽  
Robert Müller ◽  
Stefan Odenbach

This paper presents the results of an experimental study of the influence of an external magnetic field on the shear flow behaviour of a magnetic fluid based on barium hexaferrite nanoplates. With the use of rheometry, the magnetoviscosity and field-dependent yield-stress in the fluid are evaluated. The observed fluid behaviour is compared to that of ferrofluids with magnetic nanoparticles having high dipole interaction. The results obtained supplement the so-far poorly studied topic of the influence of magnetic nanoparticles’ shape on magnetoviscous effects. It is concluded that the parameter determining the observed magnetoviscous effects in the fluid under study is the ratio V2/l3, where V is the volume of the nanoparticle and l is the size of the nanoparticle in the direction corresponding to its orientation in the externally applied magnetic field.


1969 ◽  
Vol 29 (4) ◽  
pp. 680-686 ◽  
Author(s):  
R.E Rosensweig ◽  
R Kaiser ◽  
G Miskolczy

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